News about the caravan of Honduran and Guatemalan migrants fleeing gang violence and poverty to seek refugee status in the United States has been splashed across television screens for more than a week.

President Trump and members of his administration declared, with no evidence, that Middle Eastern terrorists are embedded in the crowds, hoping to infiltrate the United States. Their fearmongering is challenged by images of individual migrants, usually with children, that emphasize the humanitarian crisis the caravan represents.

These dueling interpretations — threatening vs. vulnerable — reflect a far deeper debate, one that dates back to the country’s founding, about whether Americans should be bound together by a national identity built around shared civic ideals or through common ancestral, religious or racial background. They also reflect longtime debates about whether we ought to focus on border security or whether, by keeping refugees out, the United States is failing to fulfill its promise to be a haven for the oppressed.

Our current moment has parallels with the immigration-restriction debates of the first decades of the 20th century. The United States received a record number of immigrants, mostly coming to work in the growing industries. Unlike earlier immigrant streams from more Protestant nations of northern and western Europe, the vast majority of these immigrants came from southern and eastern Europe. Many Americans welcomed them and saw their immigration as a sign of American vitality, but others worried that the fundamental character of the nation was under threat.